QCD Axial Anomaly Enhances the ηη′ Decay of the Hybrid Candidate η1(1855)

Abstract

We study the hybrid mesons with the exotic quantum numberIGJPC= 0+1−+and investigate their decays into theη η′,a1(1260)π,f1(1285)η,f1(1420)η,K*(892)K¯,K1(1270)K¯, andK1(1400)K¯channels. It is found that the QCD axial anomaly enhances the decay width of theη η′ channel although this mode is strongly suppressed by the small p-wave phase space. Our results support the interpretation of theη1(1855) recently observed by BESIII as thes¯sghybrid meson ofIGJPC= 0+1−+. The QCD axial anomaly ensures theη η′ decay mode to be a characteristic signal of the hybrid nature of theη1(1855).